An Analysis Of Correlation And It's Influencing Factors Between BMI And TSH Level

Objective:Making an analysis of correlation between body mass index(BMI)and serum thyroid stimulating hormone(TSH)level in normal range and TSH's influencing factors.Method:Select 331 patients with normal thyroid function as study objects from our hospital from December 2014 to December 2018 and collect related date of each patient,including gender,age and medical history.All the study objects were required to take physical examination to measure systolic blood pressure(SBP),diastolic blood pressure(DBP),hemoglobin(HGB),free triiodothyronine(FT3),free thyroxine(FT4),TSH,thyroid peroxidase antibody(TPOAb),thyroglobulin antibody(TGAb),thyrotrophin receptor antibody(TRAb),albumin(ALB),total bilirubin(TBIL),alanine aminotransferase(ALT),aspartate aminotransferase(AST),alkaline phosphatase(ALP),?-glutamyl transferase(GGT),cholesterol(CHO),triglyceride(TG),high-density lipoprotein cholesterol(HDL-C),low-density lipoprotein cholesterol(LDL-C),apolipoprotein A-1(ApOA1),apolipoprotein B(ApOB),blood urea nitrogen(BUN),creatinine(CREA),uric acid(UA)and fasting plasma glucose(FPG).Besides,color doppler ultrasonography was adopted to examine patients'digestive systems.The patients were grouped based on BMI.Therefore,there are 125 cases in overweight group(A group)with BMI?24kg/m~2 and 206 cases were in non-overweight group(B group)with BMI<24kg/m~2.All study objects had normal thyroid function,and TSH was within the normal reference range,that is,0.27-4.2mU/L.Statistical analysis:all data were analyzed by using SPSS22.0 software.Continuous numerical variables were expressed as x±s.Independent-samples t-test was applied to the comparison between two sample means.The difference was considered statistically significant when P<0.05.Chi-square test was used to compare classified variables and the difference was considered statistically significant when P<0.05.Spearman rank correlation analysis and Pearson correlation analysis were served in correlation analysis.Multivariate stepwise regression analysis was adopted in multiple factors analysis.Results:Serum TSH level(1.92±0.82)mIU/L in overweight group(A group)was higher than that(1.70±0.75)mIU/L in non-overweight group(B group),then the difference between the two group was statistically significant(P<0.05).There were significant differences(P<0.05)between the two groups in such aspects as gender,fatty liver,hypertension,age,SBP,DBP,FT3,HGB,ALT,AST,GGT,CHO,TG,HDL-C,LDL-C,ApOA1,ApOB,CREA,UA,FPG,while the differences of FT4,TRAb,TPOAb,TGAb,ALB,TBIL,ALP and diagnosis of diabete mellitus between the two group were not statistically significant with P>0.05.Spearman rank correlation analysis and Pearson correlation analysis showed that serum TSH level in normal range was positively correlated with BMI,ALT,AST and TG(r values were 0.117,0.118,0.124 and0.131,respectively,P<0.05),and the correlation of other indicators was not statistically significant.Multivariate stepwise regression analysis was used with TSH as dependent variable and AST,ALT,TG and BMI as independent variables,then the result showed that TG was an independent influencing factor of TSH(P=0.017).Conclusion:When TSH was in the normal reference range,subjects with larger BMI had statistically significant higher TSH level than those with smaller BMI,and there was a positive correlation between them.Among the single factors affecting BMI,TSH was significantly positively correlated with ALT,AST and TG,and TG was the independent influencing factor of TSH.